The Definition of Dyslexia

Speaker: Dr Ian Smythe

About this talk: Dr Ian Smythe provides a definition of dyslexia. He considers the logic behind the construction of a definition and applies this to his definition of dyslexia.

About the speaker:Dr Ian Smythe, a dyslexia consultant, works on specific learning difficulties in different language and cultural environments. His international work developed out of his PhD research into cognitive differences in dyslexics in different languages. He has worked with foreign governments including the Hong Kong Education Department and also non-governmental organisations - conducting workshops, lectures and seminars around the world (including lecturing in Brazil in Portuguese) with universities, dyslexia teaching organisations and local support groups.

Further information about this Talk

Various definitions of dyslexia: There have been various definitions of dyslexia and it is difficult to know which one to believe. Should you believe the British Psychological Society, the American National Institute of Child Health and Human Development, the International Dyslexia Association, the British Dyslexia Association, the European Dyslexia Association or even the Health Council of the Netherlands!

The logic behind a definition: A definition is a balance between a single word on one side and a collection of words on the other. If that single word can replace the collection of words then we have a perfect balance between the two. So we have our definition on one side and our collection of words on the other side. For example: let's look at something simple to define like a square. All we need is to have four sides of equal length, with ninety degrees at the corners and closed sides. Here it is simple to create the balance where we can have a square on one side and our collection of words on the other: "Square: An object that has four sides of equal length, corners each of 90 degrees and closed" is a perfectly balanced definition.

Defining dyslexia: Some things are harder to define. If for example we take "games" there are lots of different types (e.g. rugby, cricket, card games). All of them are very different. Rather than having a single collection of characteristics there is more of a family resemblance. This is what dyslexia is. There are lots of different characteristics but no defining characteristic. If we look at a collection of dyslexics we could find that some have one problem, some have another but all of them are different. This is why when talking about the dyslexic individual we have to remember that every dyslexic is different. If we then look at dyslexia, the question is can we get that balance? Can we find a collection of words that replace that single word? The answer is yes:

The symptom definition of dyslexia:

"Dyslexia is a difficulty in the acquisition of accurate and / or fluent word reading, spelling and writing that is neurological in origin".

This collection of words is perfectly balanced with our single word. This definition is a symptom definition: reading and writing difficulty are symptoms.

The causal definition of dyslexia: If we want to extend our definition of dyslexia we can say:

"It may be caused by a combination of difficulties in auditory and visual processing, working memory, and analysis, synthesis and storage orthographic and phonological lexica. The semantic and motor systems may also be implicated."

This is a whole series of causes, a working hypothesis. It seems to cover a lot of areas but a lot of areas involved in learning to read and write. If we accept all the different cognitive skills that we need for learning to read and write we also have to accept that all of them could actually go wrong. So all of them could be a cause which means that when it comes to an assessment we should look at all those causes.

The manifestation of dyslexia:

"The manifestation of dyslexia in any individual will depend upon not only individual cognitive differences but also the language used."

Put another way, dyslexia occurs in all languages, but the problems you have may be different in one language to that of another.

Dyslexia versus the dyslexic individual: A lot of people have questioned that the definition above misunderstands the difficulties of the dyslexic individual. There are a lot of other difficulties such as problems with left and right and tying shoelaces. What we need to remember is that the dyslexic individual had all those difficulties but that is the dyslexic individual and it is not the definition of dyslexia. The point here is that underlying causes, for example memory (difficulty of remembering words and remembering the phonological components), those memory issues may also impact on remembering how to tie shoe laces or left and right. It's that single underlying difficulty that does effect the reading and writing and does create problems for the dyslexic individual. However, the question being addressed is what is dyslexia? If we take this a little further we can also understand the other problems the dyslexic individual has. For example the phonological skills are going to impact not only on reading and writing but also note taking, listening comprehension and time management. The orthographic skills effect those, the memory skills effect those. All those cognitive difficulties will have an impact on all those learning areas but also those life skills that are so fundamental to the difficulties of the dyslexic individual. It is the difficulties in those underlying cognitive skills that are also the problems behind, for example, dyspraxia. So a memory problem could be a problem for the dyslexic individual, causing reading and writing difficulties but will also impact on motor skills. It is therefore not surprising that there can be an overlap between dyslexia, dysgraphia, and dyscalculia.

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